chore(package): update mocha to version 6.2.2

Closes #20

Author: greenkeeper[bot]

package.json

@@ -41,7 +41,7 @@
     "ignore-styles": "^5.0.1",
     "jest": "^23.6.0",
     "jsdom": "^13.0.0",
-    "mocha": "^5.2.0",
+    "mocha": "^6.2.2",
     "react-hot-loader": "^4.3.12",
     "react-test-renderer": "^16.6.0",
     "sinon": "^7.1.1",